PSI - Issue 33

Dario Milone et al. / Procedia Structural Integrity 33 (2021) 734–747 D. Milone et al./ Structural Integrity Procedia 00 (2019) 000–000

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Fig. 3. a) Implant assembly scheme; b) Inclination angle of the posterior prostheses.

Table 1 show the mechanical characteristics used for the simulations. In particular, two different mechanical characteristics have been identified for the anterior and posterior areas for cortical and cancellous bone.

Table 1. Mechanical characteristics of all components.

Poisson’s Ratio

Young’s modulus [N/mm 2 ]

Materials Prosthesis

Density [g/cm 3 ]

4.62 1.39

9.6E+04 2.6E+03 1.93E+04 2.40E+04 8.35E+02 1.04E+03

0.360 0.350 0.236 0.236 0.236 0.236

Seeger

Cortical Bone 4 Cortical Bone 6 Cancellous Bone 4 Cancellous Bone 6

1.8 1.8 1.2 1.2

2.5. Mesh and Boundary conditions

ANSYS Workbench was used to analyse all systems setup. In order to create a homogeneous and adequate mesh of the entire model, discretization tests revealed the difficulty of finding optimal solutions with a low number of elements. In particular, dimension of element was decreased in the zone of connection between Seeger and equator. Given the complexity of the geometry, second order tetragonal elements (SOLID186, average dimension 0.3 mm) were used to approximate it. As reported in (Chrcanovic et al., 2016; Röhrle and Pullan, 2007; Toro-Ibacache et al., 2016), masticatory loads were applied on molars and constraints on bone. To evaluate the performance of this system, the perfect integration between prosthesis and bone were considered. The load was applied (on the negative z direction) on the abutments number 1 and 4, while the fixed constraints was applied on the cortical bone cylinders. As reported in (Cicciù et al., 2019), 0.3 friction coefficients were applied for the connection between the parts of the prosthesis. In particular, for the contact Seeger/Equator and Seeger/abutment, as reported in the catalogue of the producer, was defined a coefficient of friction of 0.35. Finally, the contact between the abutments and the bridge was considered as rigid.